MAC7200 datasheet(744/976 Pages) FREESCALE

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Functional Description

MAC7200 Microcontroller Family Reference Manual, Rev. 2

666

Freescale Semiconductor

Figure 31-36. Single-Wire Operation (LOOPS = 1, RSRC = 1)

Enable single-wire operation by setting the LOOPS bit and the receiver source bit, RSRC, in SCI control

Setting the RSRC bit connects the receiver input to the output of the TXD pin driver. Both the transmitter

and receiver must be enabled (TE=1 and RE=1).The TXDIR bit (SCICR3[1]) determines whether the

TXD pin is going to be used as an input (TXDIR = 0) or an output (TXDIR = 1) in this mode of operation.

31.10.7 Loop Operation

In loop operation the transmitter output goes to the receiver input. The Rx Input signal is disconnected

from the eSCI.

Figure 31-37. Loop Operation (LOOPS = 1, RSRC = 0)

Enable loop operation by setting the LOOPS bit and clearing the RSRC bit in SCI control register 1

(SCICR1). Setting the LOOPS bit disables the path from the Rx Input signal to the receiver. Clearing the

RSRC bit connects the transmitter output to the receiver input. Both the transmitter and receiver must be

enabled (TE = 1 and RE = 1).

31.10.8 Modes of Operation

31.10.8.1 Run Mode

Normal mode of operation.

31.10.8.2 Doze Mode

eSCI operation in Doze mode depends on the state of the SCISDOZ bit in the SCI control register 1

(SCICR1).

•

If SCISDOZ is clear, the SCI operates normally when the system is in Doze mode.

•

If SCISDOZ is set and the system is in Doze mode, the eSCI module enters a power-conservation

state as soon as the current operation is completed. In normal SCI mode, this means the eSCI will

RXD

TRANSMITTER

RECEIVER

Tx Output Signal

Tx Input Signal

RXD

TRANSMITTER

RECEIVER

Tx Output Signal

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